Community-based Study of Celiac Disease Autoimmunity Progression in Adults

Abstract Background & Aims Celiac disease can develop at any age, but outcomes of adults with positive results from serologic tests for tissue transglutaminase antibodies (tTGA) without endoscopic determination of celiac disease (called celiac autoimmunity) have not been thoroughly evaluated. We investigated the proportion of adults with celiac autoimmunity at a community medical center and their progression to celiac disease. Methods We analyzed waste blood samples from a community clinic from 15,551 adults for tTGA and, if titers were above 2 U/mL, for endomysial antibody. The blood samples had been collected at 2 time points (median interval of 8.8 years), from 2006 through 2017. We collected data from the clinic on diagnoses of celiac disease based on duodenal biopsy analysis. Results Of the serum samples collected at the first timepoint, 15,398 were negative for tTGA and were 153 positive for tTGA (>4 U/mL). Based on medical records, 6 subjects received a diagnosis of celiac disease, for a cumulative incidence of celiac disease diagnosis of 0.06% (95% CI, 0.01%–0.11%). Forty-nine subjects with a negative result from the first serologic test for tTGA (0.32%) had a positive result from the second test. Among the 153 adults who were tTGA positive at the first time point, 31 (20%) had a subsequent diagnosis of celiac disease, 81 (53%) remained positive for tTGA without a clinical diagnosis of celiac disease, and 41 (27%) tested negative for tTGA at the second time point. Higher initial tTGA titers, female sex, and a history of hypothyroidism and autoimmune disease were associated with increased risks of subsequent diagnosis of celiac disease. Interestingly, adults whose first blood sample was positive but second blood sample was negative for tTGA were older, had lower than average initial tTGA titers, and had a higher mean body mass index than adults whose blood samples were positive for tTGA at both time points or adults later diagnosed with celiac disease. Conclusions In an analysis of serum samples collected from a community clinic an average of 8.8 years apart, we found that fewer than 1% of adults with negative results from an initial test for tTGA have a positive result in a second test. Of adults with positive results from the test for tTGA, only 20% are later diagnosed with celiac disease—the remaining individuals maintain persistent increases in tTGA without diagnoses of celiac disease or have negative results from second tests.